Wednesday, August 5, 2015

Whether having breakfast will help or hinder glucose control will also depend on its macronutrient composition and carbohydrate content. In their 2011 study Pereira et al. were able to show that a high carbohydrate, high GI breakfast will have a similarly negative impact on glucose control of adults and children as having no breakfast at all (Pereira. 2011).

Intermittent fasting (IF), i.e. skipping breakfast and/or other meals in order to stay fasted for ~16h+ per day is no longer "all the rage", but still highly popular among people who believe in its health and weight loss benefits. And in fact, there is some research (also from a couple of Ramadan studies) that appears to confirm the notion that it is healthy and may - even without deliberate caloric restriction - facilitate weight and more importantly fat loss.

On the other hand, intermittent fasting conflicts with everything we've been (falsely?) told about the benefits of frequent meals. Benefits of which SuppVersity readers know that they are quasi-non-existent, in most healthy individuals and sometimes even counter-productive in obese and diabetic individuals, where most studies refute that eating more frequently provides significant weight loss benefits in the context of a calorically restricted diet.

Now, a recent study from the Diabetes Unit, Wolfson Medical Center of the Sackler Faculty of Medicine at the Tel Aviv University, the Lund University in Sweden and the Hebrew University of Jerusalem (Jakubowicz. 2015) suggests that extending your overnight fast by skipping breakfast may have real (not just corollary) detrimental effects on habitual breakfast eaters (learn why this is important) who are suffering from type II diabetes (with glycated hemoglobin (HbA1c) levels of 7–9% (the subjects in the study at hand were more than just pre-diabetic).

In this group of subjects, skipping breakfast increases post-prandial hyperglycemia (PPHG) after lunch and dinner. It lowers the important GLP-1 response to the meals (learn more about how GLP-1 is important in "Eat More, Burn More and Lose Fat Like on Crack with GLP-1!?") and impairs the subjects' already messed up insulin response. More specifically,

the lunch AUC0-180 for glucose, FFA, and glucagon were 36.8, 41.1 and 14.8% higher, respectively, and the AUC0-180 for insulin and iGLP-1 17.0% and 19.0% lower, respectively, on the NoB[reakfast] day compared with the YesB[reakfast] day (P < 0.0001),

the dinner AUC0-180 for glucose, FFA, and glucagon were 26.6, 29.6, and 11.5% higher, respectively, and the the AUC0-180 for insulin and iGLP-1 were 7.9% and 16.5% lower on the NoB day compared with the YesB day (P < 0.0001), on the other hand

In conjunction with the 30% delayed insulin peak after lunch and dinner on the NoB[reakfast] day that's bad news for anyone who has pre-existing problems with managing his blood glucose levels.

Figure 1: While the increased glucose and impaired insulin and GLP1 response to lunch and dinner are bad, the skyrocketing FFA levels (+1,787.1%) could be used as fuel - by metabolically healthy individuals (data based on Jakubowicz. 2015).

The authors' conclusion that their study "shows a long-term influence [of eating / skipping] breakfast on glucose regulation that persists throughout the day" (Jakubowicz. 2015), is thus absolutely correct - at least in the short run.

Adjusted linear regression coefficients for 24h EI in T2DM patients according to EI at breakfast in % of total EI (Jarvandi. 2014).

While there are other benefits, the greatest benefit of skipping breakfast ideally is a reduced total energy consumption. If you are like the average type II diabetic of whom recent studies indicate that he will increase, not decrease, his energy intake when he skips breakfast (Jarvandi. 2014), or if you're looking at a study where the dietary prescription made it impossible to reduce the total energy intake, the overall effect of skipping breakfast on the body fat levels and metabolic health is likely going null or even negative. So, yes: Calories count - not just with intermittent fasting, by the way.

Whether the conclusion that "[b]reakfast consumption could be a successful strategy for reduction of PPHG [prostprandial hyperglycemia] in type 2 diabetes" applies to every type II diabetic is yet as questionable as the assumption that you could extrapolate the data from this acute phase study and use it to predict the long-term response in diabetics, let alone health individuals.

Figure 2: Hunger, satiety, plasma glucose and insulin in the Eaters and Skippers in the two conditions in Thomas (2015).

If we go back to Thomas' recently published study (I have discussed it in detail here), it is after all obvious that the scientists choice of subjects who consume breakfast regularly may have thwarted their results. I mean, the researchers from the University of Colorado School of Medicine and the Denver Health Medical Center have shown quite conclusively that one's breakfast habits will determine whether skipping breakfast increases insulin, hunger and blood lipids or not.

Practically speaking, the results of the previously discussed study by Thomas et al. (2015) imply that by replacing the habitual breakfast eaters in the study at hand by habitual breakfast skippers, the results could have been very different. Against that background and in view of the fact that Jakubowicz's study with its isocaloric lunch + dinner meals (700kcal) did not allow intermittent fasting to work its true, energy intake reducing magic, I would not overrate the practical significance of the study at hand.

Figure 3: In 1992 Schlundt et al. were able to show that habitual breakfast skippers and eaters will lose the most weight on a std. weight loss inter-vention if they are forced to give their beloved breakfast habits up.

This is all the more true in view of the fact that Schlundt et al. were able to show that the success of a 12-week weight loss intervention can depend on deviating from your breakfast habits. In said study obese habitual breakfast skippers and eaters lost the most weight if they had to follow an unaccustomed eating pattern (see Figure 3) - that's not necessarily in contrast to Thomas' results, though. After all, we are dealing with acute metabolic (Thomas) vs. long-term body weight (Schlundt) data and by now you should know that these are two completely different pairs of shoes.

Against that background, I'll simply repeat my previous recommendation: If you feel intermittent fasting works for you, stick to it! Be careful, though and don't tell yourself that it would make you lose weight if it does not help you to cut your energy intake - that's very unlikely | Comment on FB!

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